The invention relates to a process for recovering the overspray of aqueous coating agents during spray application in spray booths, in which process the overspray can be recycled into the aqueous coating agent used in the spray booth.
The substitution of lacquers that are diluted with organic solvents by water-dilutable systems is becoming more and more important for well-known reasons of environmental protection. The use of water-dilutable systems results in the air being polluted to a lesser degree or even not at all as a result of solvent emissions. A general weakness when processing coating agents such as water-dilutable lacquers by spray application is presented, however, by problems resulting from the disposal of the overspray (lacquer mist); these problems arise in particular with large-scale series lacquering, in the automobile industry for example.
It is known how to cleanse the exhaust air of spray booths by washing out with water in order to get rid of the overspray. For example, in DE-A1-29 45 523 a process is described in which the overspray of conventional solvent-dilutable lacquers is washed out with water, whereupon the wash-water is subjected to ultrafiltration.
In DE-A1-32 27 22 a similar system is described for the disposal of the overspray accruing during lacquering with water-based lacquers.